1. Field of the Invention
This invention relates to a condensate separator, especially for a portable smoke or gas analyzer, and more particularly relates to condensate separator for a gas analyzer having a Peltier element in the condensation chamber, which is in direct contact with the test gas to cool the test gas below the dew point thus causing condensation.
2. Description of the Related Art
To analyze flue gases from furnaces and exhaust from gas engines, a test gas is drawn in through a test gas probe and fed to an analyzer. To achieve adequate analysis results, it is important for the test gas to be properly prepared. This process typically involves removing moisture and dirt particles from the test gas.
The test gas is conducted by the probe through a test gas tube to the analyzer. If condensate from the test gas precipitates in the test gas tube, the test gas flowing through the test gas tube may contact the precipitated condensate for a relatively long period of time. Consequently, components of the test gas such as NO.sub.2 and SO.sub.2 may become trapped by the condensate, reducing the effective concentration of such components in the test gas, and thus leading to a distortion of the measured values of these components.
One known way to avoid occurrence of this source of measurement error is to heat the test gas tube and to provide a cooled condensate separator between the sampling probe and the analyzer. By heating the tube, it is possible to ensure that the test gas flowing therein will be maintained at or above the dew point temperature so that moisture will not condense in the test gas tube. Condensate separation then takes place exclusively and completely in a short space along the gas flow path, namely within the cooled condensate separator connected downstream from the test gas tube. The length of contact between the test gas and the liquid condensate is therefore limited to the vicinity of the condensate separator itself, so that only small quantities of NO.sub.2 and SO.sub.2 are trapped by the condensate. The concentrations of NO.sub.2 and SO.sub.2 in the test gas stream after passing through the condensate separator thus are practically the same as the concentrations in the flue gas to be analyzed. One example of a known condensate separator is shown in German Patent DE 42 29 177 C1.
Although the condensate separator described above has proven itself in principle, it suffers from a number of disadvantages. For example, problems occur when this apparatus is implemented in a mobile gas analyzer, designed for example for use by heating technicians or chimney sweeps, since a relatively large amount of energy is required to heat the test gas tube and to cool the gas in the condensate separator. These high energy requirements reduce the effective operating time of mobile gas analyzers, which are necessarily battery powered. Accordingly, frequent battery replacement is required.
The reasons for this comparatively poor efficiency are diverse in nature. In particular, the housing surrounding the condensate chamber must be cooled as a whole, and high energy is required for the cooling process because of the high thermal capacity of the housing. Moreover, high energy losses occur as a result of the loss of heat to the environment, which can be eliminated to only a very limited extent by insulation surrounding the housing. These and other problems limit the usefulness of certain known portable gas analyzers.